Tag: All out war

It’s a bit of a buzzword in the news recently: antibiotic resistance. I mean, yes, it is actually a pretty serious issue – and it does deserve the media hurrah it’s been getting… but is it solvable?

I think it’s best we begin with the idea that there are good microbes and there are bad microbes. Humans are made up of around 35 trillion cells, and are inhabited by (drumroll please) about 100 trillion microbes – an almost 3:1 ratio.

Just to clear this up, a microbe (or “microorganism”) is quite literally just a tiny tiny organism which is, in fact, so tiny that we can’t see it with the naked eye. They are some of the most ancient creatures inhabiting the earth, and include bacteria, archaea, fungi, protists and potentially viruses. I use the word ‘potentially’, as it’s still hotly debated whether or not viruses can be technically classified as alive.

What’s more, although microbes would probably be quite fine without us (and our pesky modern medicines), we would categorically be unable to exist without them.

We’re all familiar with the bad or “pathogenic” (disease causing) microbes: if you’ve ever caught a cold, or had a spot, or contracted food poisoning, you have them to thank. Usually these come from outside the body, but if the body’s natural order is disturbed then a useful “good” microbe can grow out of control and wreak havoc.

On the other side of things, good microbes can protect us by crowding out some of their dangerous relatives that can cause disease. They can help us digest our food, and can synthesise important vitamins for us.

So on to antibiotics.

Antibiotics are popularly prescribed drugs which work by altering things that bacterial cells have but human cells don’t. For example, penicillin stops bacteria from building it’s cell wall – a property that human cells don’t have. The key thing to remember here is that antibiotics only work on bacteria, and don’t damage your cells.

Now, unfortunately for us, the bacteria don’t just sit there and take it. The problem can be split into two parts: 1) the ability of bacteria to mutate their DNA and 2) their ability to pass on little packets of DNA to a neighbouring bacterium.

Mutations are rare and spontaneous changes in the bacteria’s DNA which can lead to many different types of “resistance” (which just means being able to evade the effects of antibiotics). For example, some mutations could let the bacteria develop useful chemicals called enzymes which can inactivate the ingredients in the antibiotic.

This results in a “selection pressure”: bacteria which can resist the attack are much more likely to survive and reproduce, passing on the helpful gene and replacing all the bacteria which were killed off. In this way, pretty soon all the bacteria in that population will have the gene – and so the antibiotic will be rendered useless. This is called “vertical gene transfer”, and effectively means the genes are being passed down the family tree.

By NIAID [Public domain], via Wikimedia Commons

The other mechanism is called “acquired resistance” and works through a type of bacterial mating called conjugation. This is when bacteria can exchange genetic material encoding the helpful resistance genes, letting it spread through the population. This is known as “horizontal gene transfer”, as the genes are being passed from one bacteria to the next.

The overuse of antibiotics leads to a greater selection pressure, and so effectively we’re speeding up the spread of resistance in bacteria. In some countries and over the Internet, you don’t need a prescription to buy antibiotics, and some people use them to treat viruses…which they don’t actually work against.

A superbug describes a bacteria that has collected all these little packages of resistance, making it immune to a whole load of antibiotics. If the name MRSA sounds familiar, it’s because it made headlines a few years back as a big big problem in hospitals. Methicillin-resistant Staphylococcus aureus is a bacterial superbug which is resistant to many of the commonly used antibiotics.

The real worry is that one day soon a bacteria will come along and we just won’t be able to treat it. This could mean a return to the pre-antibiotics era – where you could go deaf from an ear infection, or even die from a throat infection.

It’s a pretty bleak looking future.

So what can we do about it?

Really, the only possible thing to do is to try to slow down our use of antibiotics so we can be sure they’ll still pack a punch when we use them. If you’re prescribed antibiotics, make sure you finish the whole course even if you feel better – or else the bacteria could become resistant. Agricultural antibiotic use should also be wound back a bit, as it’s helping to create these antibiotic resistant bacteria which can jump ship to humans, and cause even more problems. Many animals are pumped full of antibiotics to either make them grow more quickly or to prevent disease which, due to the living conditions, could rapidly spread throughout the farm… but is the trade-off really worth it?

The other point to mention is that antibiotics work against both good and bad bacteria. Yes, they help to kill off what’s making us ill, but they can also disturb the balance of our body in the process – which can lead to digestion problems, or increase susceptibility to infection. So it’s doubly important to only use them when really necessary, and to trust your doctor!

Below is a great video which sums up the causes of antibiotic resistance – give it a watch if you’re interested!